Curable composition, curing product, and method for using curable composition

ABSTRACT

The present invention is: a curable composition comprising a component (A) and a component (B) in a mass ratio (component (A):component (B)) of 100:0.1 to 100:50; a cured product obtained by curing the curable composition; and a method for using the curable composition as an optical device-securing adhesive or an optical device sealing material. The component (A) is a silane compound polymer that is represented by a formula (a-1) (where in the formula: R 1  is a group selected from an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, and a substituted or unsubstituted aryl group having 6 to 20 carbon atoms, Z is a hydroxyl group, an alkoxy group having 1 to 10 carbon atoms, or a halogen atom, m is a positive integer, and n and o are independently 0 or a positive integer, provided that a plurality of R 1  are either identical or different, and a plurality of Z are either identical or different), and the component (B) is a silane coupling agent that comprises a sulfur atom-containing functional group in its molecule. 
       (R 1 SiO 3/2 ) m (R 1 SiZO 2/2 ) n (R 1 SiZ 2 O 1/2 ) o    (a-1)

TECHNICAL FIELD

The present invention relates to a curable composition that produces a cured product that exhibits excellent transparency, heat resistance, and adhesion, and also exhibits excellent durability with respect to a change in temperature, a cured product obtained by curing the curable composition, and a method for using the curable composition as an optical device adhesive or an optical device sealing material.

BACKGROUND ART

A curable composition has been used as an optical device-securing composition (e.g., optical device adhesive or optical device sealing material) when producing a sealed optical device.

Examples of the optical device include a light-emitting device (e.g., laser (e.g., semiconductor laser diode (LD)) and light-emitting diode (LED)), a light-receiving device, a hybrid optical device, an optical integrated circuit, and the like. In recent years, an optical device that emits blue light or white light (i.e., an optical device that has a shorter emission peak wavelength) has been developed, and widely used. There is a tendency that the brightness of a light-emitting device having a short emission peak wavelength is significantly increased, and the amount of heat generated by such an optical device further increases.

Along with a recent increase in the brightness of an optical device, a cured product of an optical device-securing composition may deteriorate, and show a decrease in adhesion since the cured product is exposed to higher-energy light or higher-temperature (heat) generated by the optical device for a long time.

Patent Literature 1 to 3 propose an optical device-securing composition that includes a polysilsesquioxane compound as the main component in order to solve the above problem.

However, it may be difficult to obtain a cured product that exhibits sufficient heat resistance and transparency while maintaining sufficient adhesion using the optical device-securing compositions disclosed in Patent Literature 1 to 3 that include a polysilsesquioxane compound as the main component.

Along with a recent increase in the brightness and the lifetime of an optical device, an optical device-securing material used for an optical device has also been desired to exhibit excellent durability with respect to a change in temperature.

Therefore, development of a curable composition that produces a cured product that exhibits excellent transparency, heat resistance, and adhesion, and also exhibits excellent durability with respect to a change in temperature has been desired.

CITATION LIST Patent Literature

-   Patent Literature 1: JP-A-2004-359933 -   Patent Literature 2: JP-A-2005-263869 -   Patent Literature 3: JP-A-2006-328231

SUMMARY OF INVENTION Technical Problem

The invention was conceived in view of the above situation. An object of the invention is to provide a curable composition that produces a cured product that exhibits excellent transparency, heat resistance, and adhesion, and also exhibits excellent durability with respect to a change in temperature, a cured product obtained by curing the curable composition, and a method for using the curable composition as an optical device adhesive or an optical device sealing material.

Solution to Problem

The inventors of the invention have conducted extensive studies in order to solve the above problems. As a result, the inventors found that a composition that includes a specific silane compound polymer and a silane coupling agent that includes a sulfur atom-containing functional group in its molecule in a specific ratio, produces a cured product that exhibits excellent transparency, heat resistance, and adhesion, and also exhibits excellent durability with respect to a change in temperature. This finding has led to the completion of the invention.

Several aspects of the invention provide the following curable composition (see (1) to (8)), cured product (see (9) and (10)), and method for using a curable composition (see (11) and (12)).

-   (1) A curable composition including a component (A) and a     component (B) in a mass ratio (component (A):component (B)) of     100:0.1 to 100:50,

the component (A) being a silane compound polymer that is represented by the following formula (a-1),

(R¹SiO_(3/2))_(m)(R¹SiZO_(2/2))_(n)(R¹SiZ₂O_(1/2))_(o)   (a-1)

wherein R¹ is a group selected from an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, and a substituted or unsubstituted aryl group having 6 to 20 carbon atoms, Z is a hydroxyl group, an alkoxy group having 1 to 10 carbon atoms, or a halogen atom, m is a positive integer, and n and o are independently 0 or a positive integer, provided that a plurality of R¹ are either identical or different, and a plurality of Z are either identical or different, and

the component (B) being a silane coupling agent that includes a sulfur atom-containing functional group in its molecule.

-   (2) The curable composition according to (1), wherein the silane     compound polymer used as the component (A) has a weight average     molecular weight of 1,000 to 30,000. -   (3) The curable composition according to (1), wherein the silane     coupling agent used as the component (B) is a compound among     compounds respectively represented by the following formulas (b-1)     to (b-4),

(Y¹)₃Si-A¹-SH   (b-1)

(Y¹)₃Si-A¹-S—CO—R′  (b-2)

(Y¹)₃Si-A¹-S—Si(Y²)₃   (b-3)

(Y¹)₃Si-A¹-(S)_(n)-A²-Si(Y²)₃   (b-4)

wherein Y¹ and Y² are independently an alkoxy group having 1 to 10 carbon atoms, A¹ and A² are independently a substituted or unsubstituted divalent hydrocarbon group having 1 to 20 carbon atoms, R′ is a monovalent organic group having 1 to 20 carbon atoms, and n is an integer from 1 to 4, provided that a plurality of Y¹ are either identical or different, and a plurality of Y² are either identical or different.

-   (4) The curable composition according to (1), further including a     component (C), the component (C) being a silane coupling agent that     includes a nitrogen atom-containing functional group in its     molecule. -   (5) The curable composition according to (4), wherein the silane     coupling agent used as the component (C) is a compound among     compounds respectively represented by the following formulas (c-3)     to (c-6),

wherein R^(a) are a hydroxyl group, an alkoxy group having 1 to 10 carbon atoms, or a halogen atom, R^(b) are an alkyl group having 1 to 6 carbon atoms, or a substituted or unsubstituted aryl group, provided that a plurality of R^(a) are either identical or different, and a plurality of R^(b) are either identical or different, and t is an integer from 1 to 10.

-   (6) The curable composition according to (1), further including a     component (D), the component (D) being a silane coupling agent that     includes an acid anhydride structure in its molecule. -   (7) The curable composition according to (6), wherein the silane     coupling agent used as the component (D) is a     3-(tri(C₁₋₆)alkoxysilyl)propylsuccinic anhydride. -   (8) The curable composition according to (1), the curable     composition being an optical device-securing composition. -   (9) A cured product obtained by curing the curable composition     according to (1). -   (10) The cured product according to (9), the cured product being an     optical device-securing material. -   (11) A method for using the curable composition according to (1) as     an optical device-securing adhesive. -   (12) A method for using the curable composition according to (1) as     an optical device sealing material.

Advantageous Effects of Invention

The curable composition according to one aspect of the invention can produce a cured product that exhibits excellent transparency, heat resistance, and adhesion, and also exhibits excellent durability with respect to a change in temperature.

The curable composition according to one aspect of the invention may be used to form an optical device-securing material, and may particularly suitably be used as an optical device adhesive and an optical device sealing material.

DESCRIPTION OF EMBODIMENTS

A curable composition, a cured product, and a method for using a curable composition according to the exemplary embodiments of the invention are described in detail below.

A curable composition according to one embodiment of the invention includes a component (A) and a component (B) (see below) in a mass ratio (component (A):component (B)) of 100:0.1 to 100:50.

Component (A) (Silane Compound Polymer (A))

The component (A) included in the curable composition according to one embodiment of the invention is a silane compound polymer (A) that is represented by the following formula (a-1).

(R¹SiO_(3/2))_(m)(R¹SiZO_(2/2))_(n)(R¹SiZ₂O_(1/2))_(o)   (a-1)

The repeating unit represented by —(R¹SiO_(3/2))— in the formula (a-1), the repeating unit represented by —(R¹SiZO_(2/2))— in the formula (a-1), and the repeating unit represented by —(R¹SiZ₂O_(1/2))— in the formula (a-1) are respectively represented by the following formulas (a11) to (a13). Note that “—O—” in the formulas (a11) to (a13) is an oxygen atom that is bonded to two Si atoms that are contiguous thereto.

In the formula (a-1), R¹ is a group selected from an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, and a substituted or unsubstituted aryl group having 6 to 20 carbon atoms, Z is a hydroxyl group, an alkoxy group having 1 to 10 carbon atoms, or a halogen atom, m is a positive integer, and n and o are independently 0 or a positive integer, provided that a plurality of R¹ are either identical or different, and a plurality of Z are either identical or different.

When m in the formula (a-1) is equal to or larger than 2, a plurality of repeating units represented by the formula (a11) are either the same or different. When n in the formula (a-1) is equal to or larger than 2, a plurality of repeating units represented by the formula (a12) are either the same or different. When o in the formula (a-1) is equal to or larger than 2, a plurality of repeating units represented by the formula (a13) are either the same or different.

Examples of the alkyl group having 1 to 20 carbon atoms that may be represented by R¹ include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an s-butyl group, an isobutyl group, a t-butyl group, an n-pentyl group, an n-hexyl group, an n-octyl group, an isooctyl group, an n-nonyl group, an n-decyl group, an n-dodecyl group, and the like.

Examples of the cycloalkyl group having 3 to 10 carbon atoms that may be represented by R¹ include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, and the like.

Examples of the aryl group having 6 to 20 carbon atoms (that is either substituted or unsubstituted) that may be represented by R¹ include a phenyl group, a 1-naphthyl group, a 2-naphthyl group, and the like. Examples of a substituent that may substitute the aryl group include an alkyl group such as a methyl group, an ethyl group, an n-propyl group, and a t-butyl group; a halogen atom such as a fluorine atom and a chlorine atom; an alkoxy group such as a methoxy group and an ethoxy group; and the like.

R¹ is preferably an alkyl group having 1 to 20 carbon atoms, and more preferably an alkyl group having 1 to 10 carbon atoms.

Z is a hydroxyl group, an alkoxy group having 1 to 10 carbon atoms, or a halogen atom.

Examples of the alkoxy group having 1 to 10 carbon atoms include a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, an n-butoxy group, a t-butoxy group, and the like.

Examples of the halogen atom include a chlorine atom, a bromine atom, and the like.

Z is preferably a hydroxyl group or an alkoxy group having 1 to 10 carbon atoms, and more preferably a hydroxyl group or an alkoxy group having 1 to 6 carbon atoms.

m is a positive integer, and n and o are independently 0 or a positive integer.

The silane compound polymer (A) may be a homopolymer (i.e., a polymer in which R¹ are identical), or may be a copolymer (i.e., a polymer in which R¹ are different).

When the silane compound polymer (A) is a copolymer, the silane compound polymer (A) may be a random copolymer, a block copolymer, a graft copolymer, an alternating copolymer, or the like. The silane compound polymer (A) may have a ladder-like structure, a double decker-like structure, a basket-like structure, a partially cleaved basket-like structure, a cyclic structure, or a random structure.

The weight average molecular weight (Mw) of the silane compound polymer (A) is preferably 1,000 to 30,000, more preferably 1,200 to 20,000, and particularly preferably 1,500 to 15,000. When the weight average molecular weight of the silane compound polymer (A) is within the above range, it is possible to obtain a curable composition that produces a cured product that exhibits better transparency, heat resistance, and adhesion.

The weight average molecular weight (Mw) of the silane compound polymer (A) may be determined as a standard polystyrene-equivalent value by gel permeation chromatography (GPC) that utilizes tetrahydrofuran (THF) as a solvent, for example.

The molecular weight distribution (Mw/Mn) of the silane compound polymer (A) is not particularly limited, but is normally 1.0 to 8.0, preferably 1.5 to 7.0, and particularly preferably 3.0 to 6.0. When the molecular weight distribution of the silane compound polymer (A) is within the above range, it is possible to obtain a curable composition that produces a cured product that exhibits better transparency, heat resistance, and adhesion.

Note that only one type of the silane compound polymer (A) may be used, or two or more types of the silane compound polymer (A) may be used in combination.

The silane compound polymer (A) may be produced using an arbitrary method. For example, the silane compound polymer (A) may be produced by condensing a silane compound (1) represented by the formula (1): R¹Si(OR²)_(u)(X¹)_(3-u). Note that the term “condensation” is used herein in a broad sense, and includes hydrolysis and polycondensation.

R¹ in the formula (1) is the same as defined above. R² is an alkyl group having 1 to 10 carbon atoms, X¹ is a halogen atom, and u is an integer from 0 to 3.

Examples of the alkyl group having 1 to 10 carbon atoms represented by R² include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an s-butyl group, an isobutyl group, a t-butyl group, and the like.

Examples of the halogen atom represented by X¹ include a chlorine atom, a bromine atom, and the like.

When u is equal to or larger than 2, a plurality of OR² are either identical or different. When (3-u) is equal to or larger than 2, a plurality of X¹ are either identical or different.

Specific examples of the silane compound (1) include an alkyltrialkoxysilane compound such as methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, ethyltripropoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, n-propyltripropoxysilane, n-propyltributoxysilane, n-butyltrimethoxysilane, isobutyltrimethoxysilane, n-pentyltrimethoxysilane, n-hexyltrimethoxysilane, and isooctyltriethoxysilane;

-   a cycloalkyltrialkoxysilane compound such as     cyclopropyltrimethoxysilane, cyclopropyltriethoxysilane,     cyclopropyltripropoxysilane, cyclobutyltrimethoxysilane,     cyclobutyltriethoxysilane, cyclobutyltripropoxysilane,     cyclopentyltrimethoxysilane, cyclopentyltriethoxysilane,     cyclopentyltripropoxysilane, cyclohexyltrimethoxysilane,     cyclohexyltriethoxysilane, cyclohexyltripropoxysilane,     cyclooctyltrimethoxysilane, cyclooctyltriethoxysilane, and     cyclooctyltripropoxysilane; -   an aryltrialkoxysilane compound such as phenyltrimethoxysilane,     phenyltriethoxysilane, phenyltripropoxysilane,     naphthyltrimethoxysilane, naphthyltriethoxysilane,     naphthyltripropoxysilane, 4-methylphenyltrimethoxysilane,     4-methylphenyltriethoxysilane, 4-methylphenyltripropoxysilane, and     2-chlorophenyltrimethoxysilane; -   an alkylhalogenoalkoxysilane compound such as     methylchlorodimethoxysilane, methylchlorodiethoxysilane,     methyldichloromethoxysilane, methylbromodimethoxysilane,     ethylchlorodimethoxysilane, ethylchlorodiethoxysilane,     ethyldichloromethoxysilane, ethylbromodimethoxysilane,     n-propylchlorodimethoxysilane, n-propyldichloromethoxysilane,     n-butylchlorodimethoxysilane, and n-butyldichloromethoxysilane; -   a cycloalkylhalogenoalkoxysilane compound such as     cyclopropylchlorodimethoxysilane, cyclopropylchlorodiethoxysilane,     cyclopropyldichloromethoxysilane, cyclopropylbromodimethoxysilane,     cyclobutylchlorodimethoxysilane, cyclobutylchlorodiethoxysilane,     cyclobutyldichloromethoxysilane, cyclobutylbromodimethoxysilane,     cyclopentylchlorodimethoxysilane, cyclohexylchlorodimethoxysilane,     and cyclooctylchlorodimethoxysilane; -   an arylhalogenoalkoxysilane compound such as     phenylchlorodimethoxysilane, phenylchlorodiethoxysilane,     phenyldichloromethoxysilane, phenylbromodimethoxysilane,     naphthylchlorodimethoxysilane, naphthylchlorodiethoxysilane,     naphthyldichloromethoxysilane, naphthylbromodimethoxysilane,     4-methylphenylchlorodimethoxysilane,     4-methylphenyldichloromethoxysilane,     4-methylphenylbromodimethoxysilane, and     2-chlorophenylchlorodimethoxysilane; -   an alkyltrihalogenosilane compound such as methyltrichlorosilane,     methyltribromosilane, ethyltrichlorosilane, ethyltribromosilane,     n-propyltrichlorosilane, n-propyltribromosilane,     n-butyltrichlorosilane, isobutyltrichlorosilane,     n-pentyltrichlorosilane, n-hexyltrichlorosilane, and     isooctyltrichlorosilane; -   a cycloalkyltrihalogenosilane compound such as     cyclopropyltrichlorosilane, cyclopropyltribromosilane,     cyclobutyltrichlorosilane, cyclobutyltribromosilane,     cyclopentyltrich1orosilane, cyclopentyltribromosilane,     cyclohexyltrichlorosilane, cyclohexyltribromosilane,     cyclooctyltrichlorosilane, and cyclooctyltribromosilane; -   an aryltrihalogenosilane compound such as phenyltrichlorosilane,     phenyltribromosilane, naphthyltrichlorosilane,     naphthyltribromosilane, 4-methylphenyltrichlorosilane,     4-methylphenyltribromosilane, and 2-ch1orophenyltrichlorosilane; and     the like.

These silane compounds (1) may be used either alone or in combination.

An alkyltrialkoxysilane compound, a cycloalkyltrialkoxysilane compound, and an aryltrialkoxysilane compound are preferable as the silane compound (1) since a curable composition that produces a cured product that exhibits better adhesion can be obtained.

The silane compound (1) may be condensed using an arbitrary method. For example, the silane compound (1) may be condensed by dissolving the silane compound (1) in a solvent, adding a given amount of catalyst to the solution, and stirring the mixture at a given temperature.

An acid catalyst or a base catalyst may be used as the catalyst.

Examples of the acid catalyst include an inorganic acid such as hydrochloric acid, sulfuric acid, nitric acid, and phosphoric acid; an organic acid such as methanesulfonic acid, trifluoromethanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, acetic acid, and trifluoroacetic acid; and the like.

Examples of the base catalyst include an organic base such as aqueous ammonia, trimethylamine, triethylamine, lithium diisopropylamide, lithium bis(trimethylsilyl)amide, pyridine, 1,8-diazabicyclo[5.4.0]-7-undecene, aniline, picoline, 1,4-diazabicyclo[2.2.2]octane, and imidazole; an organic base hydroxide such as tetramethylammonium hydroxide and tetraethylammonium hydroxide; a metal alkoxide such as sodium methoxide, sodium ethoxide, sodium t-butoxide, and potassium t-butoxide; a metal hydride such as sodium hydride and calcium hydride; a metal hydroxide such as sodium hydroxide, potassium hydroxide, and calcium hydroxide; a metal carbonate such as sodium carbonate, potassium carbonate, and magnesium carbonate; a metal hydrogen carbonate such as sodium hydrogen carbonate and potassium hydrogen carbonate; and the like.

The catalyst is normally used in a ratio of 0.1 to 10 mol %, and preferably 1 to 5 mol %, based on the total number of moles of the silane compound(s).

The solvent may be appropriately selected taking account of the type of silane compound and the like. Examples of the solvent include water; an aromatic hydrocarbon such as benzene, toluene, and xylene; an ester such as methyl acetate, ethyl acetate, propyl acetate, and methyl propionate; a ketone such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; an alcohol such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, s-butyl alcohol, and t-butyl alcohol; and the like. These solvents may be used either alone or in combination.

The solvent is normally used so that the total number of moles of the silane compound(s) is 0.1 to 10 mol, and preferably 0.5 to 10 mol, per liter of the solvent.

The silane compound is normally condensed (reacted) in a temperature range from 0° C. to the boiling point of the solvent (preferably 20 to 100° C.). If the reaction temperature is too low, condensation (condensation reaction) may not proceed sufficiently. If the reaction temperature is too high, it may be difficult to suppress gelation. The reaction is normally completed within 30 minutes to 20 hours.

After completion of the reaction, the mixture is neutralized by adding an aqueous solution of an alkali (e.g., sodium hydrogen carbonate) when using the acid catalyst, or neutralized by adding an acid (e.g., hydrochloric acid) when using the base catalyst. Salts produced during neutralization are removed by filtration, washing with water, or the like to obtain the target silane compound polymer.

When the silane compound polymer (A) is produced using the above method, OR² or X¹ included in the silane compound (1) remains in the silane compound polymer (A) when OR² or X¹ has not been subjected to dehydration and/or dealcoholization. Specifically, when one OR² or X¹ remains in the silane compound polymer (A), the one OR² or X¹ remains in the silane compound polymer (A) represented by the formula (a-1) as (CHR¹X⁰-D-SiZO_(2/2)). When two OR² or X¹ remain in the silane compound polymer (A), the two OR² or X¹ remain in the silane compound polymer (A) represented by the formula (a-1) as (CHR¹X⁰-D-SiZ₂O_(1/2)).

Component (B) (Silane Coupling Agent That Includes a Sulfur Atom-Containing Functional Group in its Molecule)

The curable composition according to one embodiment of the invention includes a silane coupling agent that includes a sulfur atom-containing functional group in its molecule (hereinafter may be referred to as “silane coupling agent (B)”) as the component (B). The curable composition according to one embodiment of the invention that includes the silane coupling agent (B) produces a cured product that exhibits excellent transparency, heat resistance, and adhesion, and also exhibits excellent durability with respect to a change in temperature.

The silane coupling agent (B) is not particularly limited as long as the silane coupling agent (B) includes a sulfur atom-containing functional group (e.g., thiol group (—SH), acylthio group (—S—CO—R′), sulfide group (—S—), and polysulfide group (—(S)_(n)—) (e.g., disulfide group (—S—S—) and tetrasulfide group (—S—S—S—S—))) in its molecule.

Examples of the silane coupling agent (B) include silane coupling agents respectively represented by the following formulas (b-1) to (b-4), and other silane coupling agents that include a sulfur atom-containing functional group.

(Y¹)₃Si-A¹-SH   (b-1)

(Y¹)₃Si-A¹-S—CO—R′  (b-2)

(Y¹)₃Si-A¹-S—Si(Y²)₃   (b-3)

(Y¹)₃Si-A¹-(S)_(n)-A²-Si(Y²)₃   (b-4)

wherein Y¹ and Y² are independently an alkoxy group having 1 to 10 carbon atoms, A¹ and A² are independently a substituted or unsubstituted divalent hydrocarbon group having 1 to 20 carbon atoms, R′ is a monovalent organic group having l to 20 carbon atoms, and n is an integer from 1 to 4, provided that a plurality of Y¹ are either identical or different, and a plurality of Y² are either identical or different.

Examples of the alkoxy group having 1 to 10 carbon atoms represented by Y¹ and Y² include a methoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group, an n-butoxy group, an s-butoxy group, an isobutoxy group, a t-butoxy group, and the like.

Y¹ and Y² are preferably an alkoxy group having 1 to 6 carbon atoms.

Examples of the substituted or unsubstituted divalent hydrocarbon group having 1 to 20 carbon atoms represented by A¹ and A² include an alkylene group having 1 to 20 carbon atoms, an alkenylene group having 2 to 20 carbon atoms, an alkynylene group having 2 to 20 carbon atoms, an arylene group having 6 to 20 carbon atoms, a divalent group having 7 to 20 carbon atoms obtained by combining an alkylene group, an alkenylene group, or an alkynylene group with an arylene group, and the like.

Examples of the alkylene group having 1 to 20 carbon atoms include a methylene group, an ethylene group, a propylene group, a trimethylene group, a tetramethylene group, a pentamethylene group, a hexamethylene group, and the like.

Examples of the alkenylene group having 2 to 20 carbon atoms include a vinylene group, a propenylene group, a butenylene group, a pentenylene group, and the like.

Examples of the alkynylene group having 2 to 20 carbon atoms include an ethynylene group, a propynylene group, and the like.

Examples of the arylene group having 6 to 20 carbon atoms include an o-phenylene group, an m-phenylene group, a p-phenylene group, a 2,6-naphthylene group, and the like.

Examples of a substituent that may substitute the alkylene group having 1 to 20 carbon atoms, the alkenylene group having 2 to 20 carbon atoms, and the alkynylene group having 2 to 20 carbon atoms include a halogen atom such as a fluorine atom and a chlorine atom; an alkoxy group such as a methoxy group and an ethoxy group; an alkoxycarbonyl group such as a methoxycarbonyl group and an ethoxycarbonyl group; and the like.

Examples of a substituent that may substitute the arylene group having 6 to 20 carbon atoms include a cyano group; a nitro group; a halogen atom such as a fluorine atom, a chlorine atom, and a bromine atom; an alkyl group such as a methyl group and an ethyl group; an alkoxy group such as a methoxy group and an ethoxy group; and the like.

These substituents may be bonded to the alkylene group, the alkenylene group, the alkynylene group, and the arylene group at an arbitrary position. A plurality of identical or different substituents may be bonded to the alkylene group, the alkenylene group, the alkynylene group, and the arylene group.

Examples of the divalent group obtained by combining a substituted or unsubstituted alkylene group, a substituted or unsubstituted alkenylene group, or a substituted or unsubstituted alkynylene group with a substituted or unsubstituted arylene group include a group in which at least one group among a substituted or unsubstituted alkylene group, a substituted or unsubstituted alkenylene group, and a substituted or unsubstituted alkynylene group is linearly bonded to at least one substituted or unsubstituted arylene group, and the like. Specific examples of the divalent group include the groups respectively represented by the following formulas, and the like.

A¹ and A² are preferably an alkylene group having 1 to 4 carbon atoms (e.g., methylene group, ethylene group, propylene group, trimethylene group, or tetramethylene group).

R′ is not particularly limited as long as —CO—R′ can function as a protecting group. Examples of the monovalent organic group having 1 to 20 carbon atoms represented by R′ include an alkyl group such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, an s-butyl group, a t-butyl group, an n-pentyl group, an n-hexyl group, an n-heptyl group, an n-octyl group, an n-nonyl group, an n-decyl group, an n-undecyl group, and an n-dodecyl group; a substituted or unsubstituted phenyl group; and the like.

Examples of a substituent that may substitute the phenyl group (that is substituted or unsubstituted) that may be represented by R′ include an alkyl group such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an s-butyl group, an isobutyl group, a t-butyl group, an n-pentyl group, and an n-hexyl group; a halogen atom such as a fluorine atom, a chlorine atom, and a bromine atom; an alkoxy group such as a methoxy group and an ethoxy group; and the like.

R′ is preferably an alkyl group having 1 to 20 carbon atoms, and more preferably an alkyl group having 1 to 10 carbon atoms.

n is an integer from 1 to 4, preferably 1, 2, or 4, and more preferably 2 or 4.

Examples of the silane coupling agent represented by the formula (b-1) include a mercaptoalkyltrialkoxysilane such as mercaptomethyltrimethoxysilane, mercaptomethyltriethoxysilane, mercaptomethyltripropoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, 2-mercaptoethyltripropoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, and 3-mercaptopropyltripropoxysilane.

Examples of the silane coupling agent represented by the formula (b-2) include an alkanoylthioalkyltrialkoxysilane compound such as 2-hexanoylthioethyltrimethoxysilane, 2-hexanoylthioethyltriethoxysilane, 2-octanoylthioethyltrimethoxysilane, 2-octanoylthioethyltriethoxysilane, 2-decanoylthioethyltrimethoxysilane, 2-decanoylthioethyltriethoxysilane, 3-hexanoylthiopropyltrimethoxysilane, 3-hexanoylthiopropyltriethoxysilane, 3-octanoylthiopropyltrimethoxysilane, 3-octanoylthiopropyltriethoxysilane, 3-decanoylthiopropyltrimethoxysilane, and 3-decanoylthiopropyltriethoxysilane.

Examples of the silane coupling agent represented by the formula (b-3) include 2-trimethoxysilylethylsulfanyltrimethoxysilane, 2-trimethoxysilylethylsulfanyltriethoxysilane, 2-triethoxysilylethylsulfanyltrimethoxysilane, 2-triethoxysilylethylsulfanyltriethoxysilane, 3-trimethoxysilylpropylsulfanyltrimethoxysilane, 3-trimethoxysilylpropylsulfanyltriethoxysilane, 3-triethoxysilylpropylsulfanyltrimethoxysilane, 3-triethoxysilylpropylsulfanyltriethoxysilane, and the like.

Examples of the silane coupling agent represented by the formula (b-4) include a disulfide compound such as bis(2-trimethoxysilylethyl)disulfide, bis(2-triethoxysilylethyl)disulfide, bis(3-trimethoxysilylpropyl)disulfide, bis(3-triethoxysilylpropyl)disulfide, bis(4-trimethoxysilylbutyl)disulfide, and bis(4-triethoxysilylbutyl)disulfide; a tetrasulfide compound such as bis(2-triethoxysilylethyl)tetrasulfide, bis(3-trimethoxysilylpropyl)tetrasulfide, and bis(3-triethoxysilylpropyl)tetrasulfide; and the like.

Examples of other silane coupling agents that include a sulfur atom-containing functional group include a thiocarbamoyl group-containing silane coupling agent such as 3-trimethoxysilylpropyl-N,N-dimethylthiocarbamoyl tetrasulfide, 3-triethoxysilylpropyl-N,N-dimethylthiocarbamoyl tetrasulfide, 2-triethoxysilylethyl-N,N-dimethylthiocarbamoyl tetrasulfide, and 2-trimethoxysilylethyl-N,N-dimethylthiocarbamoyl tetrasulfide; a benzothiazolyl group-containing silane coupling agent such as 3-trimethoxysilylpropylbenzothiazolyl tetrasulfide and 3-triethoxysilylpropylbenzothiazolyl tetrasulfide; a (meth)acrylate group-containing silane coupling agent (the term “(meth)acrylate” refers to an acrylate or a methacrylate) such as 3-triethoxysilylpropyl(meth)acrylate monosulfide and 3-trimethoxysilylpropyl(meth)acrylate monosulfide; a polysulfide group-containing silane coupling agent such as a bis(3-triethoxysilylpropyl)polysulfide, a bis(2-triethoxysilylpropyl)polysulfide, and a bis(4-triethoxysilylbutyl)polysulfide; and the like.

Among these, the silane coupling agent represented by the formula (b-1) and the silane coupling agent represented by the formula (b-3) are preferable, the silane coupling agent represented by the formula (b-1) in which Y¹ is an alkoxy group having 1 to 10 carbon atoms (e.g., 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, 2-mercaptoethyltripropoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, and 3-mercaptopropyltripropoxysilane), and the silane coupling agent represented by the formula (b-3) in which Y′ and Y² are an alkoxy group having 1 to 10 carbon atoms (e.g., 2-trimethoxysilylethylsulfanyltrimethoxysilane, 2-trimethoxysilylethylsulfanyltriethoxysilane, 2-triethoxysilylethylsulfanyltrimethoxysilane, 2-triethoxysilylethylsulfanyltriethoxysilane, 3-trimethoxysilylpropylsulfanyltrimethoxysilane, 3-trimethoxysi lylpropylsulfanyltriethoxysil ane, 3-triethoxysilylpropylsulfanyltrimethoxysilane, and 3-triethoxysilylpropylsulfanyltriethoxysilane) are more preferable, and 3-mercaptopropyltrimethoxysilane and 3-trimethoxysilylpropylsulfanyltriethoxysilane are still more preferable as the component (B) used in connection with one embodiment of the invention.

These silane coupling agents (B) may be used either alone or in combination.

The curable composition includes the component (A) and the component (B) in a mass ratio (component (A):component (B)) of 100:0.1 to 100:50, preferably 100:0.4 to 100:20, and particularly preferably 100:0.8 to 100:13.

The curable composition according to one embodiment of the invention that includes the component (A) and the component (B) in a mass ratio within the above range produces a cured product that exhibits excellent transparency, heat resistance, and adhesion, and also exhibits excellent durability with respect to a change in temperature.

The curable composition according to one embodiment of the invention may include an additional component other than the above components as long as the object of the invention is not impaired.

Examples of the additional component include a component (C) (i.e., a silane coupling agent that includes a nitrogen atom-containing functional group in its molecule), a component (D) (i.e., a silane coupling agent that includes an acid anhydride structure in its molecule), an antioxidant, a UV absorber, a light stabilizer, a diluent, and the like.

The component (C) is a silane coupling agent that includes a nitrogen atom-containing functional group in its molecule (hereinafter may be referred to as “silane coupling agent (C)”).

The curable composition that includes the component (C) in addition to the component (B) produces a cured product that exhibits better transparency, heat resistance, and adhesion.

The silane coupling agent (C) is not particularly limited as long as the silane coupling agent (C) includes a nitrogen atom in its molecule. Examples of the silane coupling agent (C) include a silane coupling agent represented by the following formula (c-1) and a silane coupling agent represented by the following formula (c-2).

(R^(a))₃SiR^(c)   (c-1)

(R^(a))₂(R^(b))SiR^(c)   (c-2)

In the formulas (c-1) and (c-2), R^(a) are a hydroxyl group, an alkoxy group having 1 to 10 carbon atoms, or a halogen atom. A plurality of R^(a) are either identical or different.

Examples of the alkoxy group having 1 to 10 carbon atoms include a methoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group, an n-butoxy group, an s-butoxy group, an isobutoxy group, a t-butoxy group, and the like.

Examples of the halogen atom include a chlorine atom, a bromine atom, and the like.

R^(a) are preferably an alkoxy group having 1 to 10 carbon atoms, and more preferably an alkoxy group having 1 to 6 carbon atoms.

R^(b) is an alkyl group having 1 to 6 carbon atoms, or a substituted or unsubstituted aryl group.

Examples of the alkyl group having 1 to 6 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a t-butyl group, and the like.

Examples of the substituted or unsubstituted aryl group include a phenyl group, a 4-chlorophenyl group, a 4-methylphenyl group, and the like.

R^(c) is an organic group having 1 to 10 carbon atoms that includes a nitrogen atom. R^(c) is optionally further bonded to a group that includes a silicon atom.

Specific examples of the organic group having 1 to 10 carbon atoms represented by R^(c) include an N-2-(aminoethyl)-3-aminopropyl group, a 3-aminopropyl group, an N-(1,3-dimethylbutylidene)aminopropyl group, a 3-ureidopropyl group, an N-phenylaminopropyl group, and the like.

Examples of the compound represented by the formula (c-1) or (c-2) in which Re is an organic group that is further bonded to a group that includes a silicon atom, include a compound in which R^(c) is further bonded to a group that includes a silicon atom through an isocyanurate skeleton to form an isocyanurate-based silane coupling agent, and a compound in which R^(c) is further bonded to a group that includes a silicon atom through a urea skeleton to form a urea-based silane coupling agent.

Among these, an isocyanurate-based silane coupling agent and a urea-based silane coupling agent are preferable, and an isocyanurate-based silane coupling agent and a urea-based silane coupling agent that include four or more groups represented by R^(a) are more preferable, since a cured product that exhibits higher adhesion can be obtained.

Examples of the isocyanurate-based silane coupling agent that includes four or more groups represented by R^(a) include a compound represented by the following formula (c-3) and a compound represented by the following formula (c-4).

Examples of the urea-based silane coupling agent that includes four or more groups represented by R^(a) include a compound represented by the following formula (c-5) and a compound represented by the following formula (c-6).

In the formulas (c-3) to (c-6), R^(a) and R^(b) are the same as defined above. A plurality of R^(a) are either identical or different, and a plurality of le are either identical or different.

t are an integer from 1 to 10, preferably an integer from 1 to 6, and particularly preferably 3.

The groups represented by —(CH₂)_(t)—Si(R^(a))₃ are either identical or different, and the groups represented by —(CH₂)_(t)—Si(R^(a))₂(R^(b)) are either identical or different.

Specific examples of the compound represented by the formula (c-3) include a 1,3,5-N-tris[(tri(C₁₋₆)alkoxy)silyl(C₁₋₁₀)alkyl]isocyanurate such as 1,3,5-N-tris(3-trimethoxysilylpropyl)isocyanurate, 1,3,5-N-tris(3-triethoxysilylpropyl)isocyanurate, 1,3,5-N-tris(3-trisoipropoxysilylpropyl)isocyanurate, and 1,3,5-N-tris(3-tributoxysilylpropyl)isocyanurate; a 1,3,5-N-tris(trihalogenosilyl(C₁₋₁₀)alkyl)isocyanurate such as 1,3,5-N-tris(3-trichlorosilylpropyl)isocyanurate and 1,3,5-N-tris(3-trichlorosilylpropyl)isocyanurate; and the like.

Specific examples of the compound represented by the formula (c-4) include a 1,3,5-N-tris[(di(C₁₋₆)alkoxy)((C₁₋₆)alkyl)silyl(C₁₋₁₀)alkyl)]isocyanurate such as 1,3,5-N-tris(3-dimethoxymethylsilylpropyl)isocyanurate, 1,3,5-N-tris(3-dimethoxyethylsilylpropyl)isocyanurate, 1,3,5-N-tris(3-dimethoxyisopropylsilylpropyl)isocyanurate, 1,3,5-N-tris(3-dimethoxy-n-propylsilylpropyl)isocyanurate, 1,3,5-N-tris(3-diethoxymethylsilylpropyl)isocyanurate, 1,3,5-N-tris(3-diethoxyethylsilylpropyl)isocyanurate, 1,3,5-N-tris(3-diethoxyisopropylsilylpropyl)isocyanurate, 1,3,5-N-tris(3-diethoxy-n-propylsilylpropyl)isocyanurate, 1,3,5-N-tris(3-diisopropoxymethylsilylpropyl)isocyanurate, 1,3,5-N-tris(3-diisopropoxyethylsilylpropyl)isocyanurate, 1,3,5-N-tris(3-diisopropoxyisopropylsilylpropyl)isocyanurate, 1,3,5-N-tris(3-diisopropoxy-n-propylsilylpropyl)isocyanurate, 1,3,5-N-tris(3-dibutoxymethylsilylpropyl)isocyanurate, 1,3,5-N-tris(3-dibutoxyethylsilylpropyl)isocyanurate, 1,3,5-N-tris(3-dibutoxyisopropylsilylpropyl)isocyanurate, and 1,3,5-N-tris(3-dibutoxy-n-propylsilylpropyl)isocyanurate; a 1,3,5-N-tris[(di(C₁₋₆)alkoxy)((C₆₋₂₀)aryl)silyl(C₁₋₁₀)alkyl]isocyanurate such as 1,3,5-N-tris(3-dimethoxyphenylsilylpropyl)isocyanurate, 1,3,5-N-tris(3-diethoxyphenylsilylpropyl)isocyanurate, 1,3,5-N-tris(3-diisopropoxyphenylsilylpropyl)isocyanurate, and 1,3,5-N-tris(3-dibutoxyphenylsilylpropyl)isocyanurate; and the like.

Specific examples of the compound represented by the formula (c-5) include an N,N′-bis[(tri(C₁₋₆)alkoxysilyl)(C₁₋₁₀)alkyl]urea such as N,N′-bis(3-trimethoxysilylpropyl)urea, N,N′-bis(3-triethoxysilylpropyl)urea, N,N′-bis(3-tripropoxysilylpropyl)urea, N,N′-bis(3-tributoxysilylpropyl)urea, and N,N′-bis(2-trimethoxysilylethyl)urea; an N,N′-bis(trihalogenosilyl(C₁₋₁₀)alkyl)urea such as N,N′-bis(3-trichlorosilylpropyl)urea and N,N′-bis(3-tribromosilylpropyl)urea; and the like.

Specific examples of the compound represented by the formula (c-6) include an N,N′-bis(di(C₁₋₆)alkoxy(C₁₋₆)alkylsilyl(C₁₋₁₀)alkyl)urea such as N,N′-bis(3-dimethoxymethylsilylpropyl)urea, N,N′-bis(3-dimethoxyethylsilylpropyl)urea, and N,N′-bis(3-diethoxymethylsilylpropyl)urea; an N,N′-bis(di(C₁₋₆alkoxy(C₆₋₂₀)arylsilyl(C₁₋₁₀)alkyl)urea such as N,N′-bis(3-dimethoxyphenylsilylpropyl)urea and N,N′-bis(3-diethoxyphenylsilylpropyl)urea; an N,N′-bis(dihalogeno(C₁₋₆)alkylsilyl(C₁₋₁₀)alkyl)urea such as N,N′-bis(3-dichloromethylsilylpropyl)urea; an N,N′-bis(dihalogeno(C₆₋₂₀)arylsilyl(C₁₋₁₀)alkyl)urea such as N,N′-bis(3-dichlorophenylsilylpropyl)urea; and the like.

These compounds may be used either alone or in combination.

It is preferable to use 1,3,5-N-tris(3-trimethoxysilylpropyl)isocyanurate, 1,3,5,-N-tris(3-triethoxysilylpropyl)isocyanurate, N,N′-bis(3-trimethoxysilylpropyl)urea, or N,N′-bis(3-triethoxysilylpropyl)urea as the component (C). It is particularly preferable to use 1,3,5-N-tris(3-trimethoxysilylpropyl)isocyanurate or 1,3,5,-N-tris(3-triethoxysilylpropyl)isocyanurate as the component (C).

When using the component (C), the component (C) is preferably used so that the mass ratio (component (A):component (C)) is 100:0.3 to 100:30, and more preferably 100:5 to 100:20.

The curable composition according to one embodiment of the invention that includes the component (C) in a mass ratio within the above range produces a cured product that exhibits better transparency, heat resistance, and adhesion, and also exhibits excellent durability with respect to a change in temperature.

The component (D) is a silane coupling agent that includes an acid anhydride structure in its molecule (hereinafter may be referred to as “silane coupling agent (D)”).

The curable composition that includes the component (D) in addition to the component (B) produces a cured product that exhibits better transparency, heat resistance, and adhesion.

Examples of the silane coupling agent (D) include a silane coupling agent represented by the following formula (d-1).

wherein Q is an acid anhydride structure, R^(d) is an alkyl group having 1 to 6 carbon atoms, or a substituted or unsubstituted phenyl group, R^(c) is a hydroxyl group, an alkoxy group having 1 to 10 carbon atoms, or a halogen atom, i is an integer from 1 to 3, j is an integer from 0 to 2, and k is an integer from 1 to 3, provided that i+j+k=4, a plurality of Q are either identical or different when a plurality of Q are present, a plurality of R^(d) are either identical or different when a plurality of R^(d) are present, and a plurality of R^(e) are either identical or different when a plurality of R^(e) are present.

Examples of Q include the groups respectively represented by the following formulas (Q1) to (Q4), and the like. The group represented by the formula (Q1) is particularly preferable.

wherein h is an integer from 0 to 10.

Examples of the alkyl group having 1 to 6 carbon atoms that may be represented by R^(d) include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a t-butyl group, and the like.

Examples of the substituted or unsubstituted phenyl group that may be represented by R^(d) include a phenyl group, a 4-chlorophenyl group, a 4-methylphenyl group, and the like.

Examples of the alkoxy group having 1 to 10 carbon atoms that may be represented by R^(e) include a methoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group, an n-butoxy group, an s-butoxy group, an isobutoxy group, a t-butoxy group, and the like.

Examples of the halogen atom that may be represented by R^(e) include a chlorine atom, a bromine atom, and the like.

R^(e) is preferably an alkoxy group having 1 to 10 carbon atoms, and more preferably an alkoxy group having 1 to 6 carbon atoms.

A compound represented by the following formula (d-2) is preferable as the compound represented by the formula (d-1).

wherein R^(e), h, i, j, and k are the same as defined above.

h is preferably an integer from 2 to 8, more preferably 2 or 3, and particularly preferably 3.

Specific examples of the silane coupling agent represented by the formula (d-2) include a tri(C₁₋₆)alkoxysilyl(C₂₋₈)alkylsuccinic anhydride such as 2-(trimethoxysilyl)ethylsuccinic anhydride, 2-(triethoxysilyl)ethylsuccinic anhydride, 3-(trimethoxysilyl)propylsuccinic anhydride, and 3-(triethoxysilyl)propylsuccinic anhydride; a di(C₁₋₆)alkoxymethylsilyl(C₂₋₈)alkylsuccinic anhydride such as 2-(dimethoxymethylsilyl)ethylsuccinic anhydride; a (C₁₋₆)alkoxydimethylsilyl(C₂₋₈)alkylsuccinic anhydride such as 2-(methoxydimethylsilyl)ethylsuccinic anhydride;

-   a trihalogenosilyl(C₂₋₈)alkylsuccinic anhydride such as     2-(trichlorosilyl)ethylsuccinic anhydride and     2-(tribromosilyl)ethylsuccinic anhydride; a     dihalogenomethylsilyl(C₂₋₈)alkylsuccinic anhydride such as     2-(dichloromethylsilyl)ethylsuccinic anhydride; a     halogenodimethylsilyl(C₂₋₈)alkylsuccinic anhydride such as     2-(chlorodimethylsilyl)ethylsuccinic anhydride; and the like.

Among these, a tri(C₁₋₆)alkoxysilyl(C₂₋₈)alkylsuccinic anhydride is preferable, and 3-(trimethoxysilyl)propylsuccinic anhydride and 3-(triethoxysilyl)propylsuccinic anhydride are particularly preferable.

These silane coupling agents (D) may be used either alone or in combination.

When using the component (D), the component (D) is preferably used so that the mass ratio (component (A):component (D)) is 100:0.3 to 100:30, and more preferably 100:0.5 to 100:10.

The curable composition according to one embodiment of the invention that includes the component (D) in a mass ratio within the above range produces a cured product that exhibits better transparency, heat resistance, and adhesion, and also exhibits excellent durability with respect to a change in temperature.

The antioxidant is added to the curable composition in order to prevent deterioration due to oxidation during heating. Examples of the antioxidant include a phosphorus-based antioxidant, a phenol-based antioxidant, a sulfur-based antioxidant, and the like.

Examples of the phosphorus-based antioxidant include a phosphite, an oxaphosphaphenanthrene oxide, and the like.

Examples of the phenol-based antioxidant include a monophenol, a bisphenol, a polyphenol, and the like.

Examples of the sulfur-based antioxidants include dilauryl 3,3′-thiodipropionate, dimyristyl 3,3′-thiodipropionate, distearyl 3,3′-thiodipropionate, and the like.

These antioxidants may be used either alone or in combination. The antioxidant is normally used in a ratio of 10 mass % or less based on the component (A).

The UV absorber is added to the curable composition in order to improve the light resistance of the resulting cured product.

Examples of the UV absorber include a salicylic acid, a benzophenone, a benzotriazole, a hindered amine, and the like.

These UV absorbers may be used either alone or in combination.

The UV absorber is normally used in a ratio of 10 mass % or less based on the component (A).

The light stabilizer is added to the curable composition in order to improve the light resistance of the resulting cured product.

Examples of the light stabilizer include a hindered amine such as poly[{6-(1,1,3,3-tetramethylbutyeamino-1,3,5-triazine-2,4-diyl}{(2,2,6,6-tetramethyl-4-piperidine)imino}hexamethylene{(2,2,6,6-tetramethyl-4-piperidine)imino}], and the like.

These light stabilizers may be used either alone or in combination.

The light stabilizer is normally used in a ratio of 10 mass % or less based on the component (A).

The diluent is added to the curable composition in order to adjust the viscosity of the curable composition.

Examples of the diluent include glycerol diglycidyl ether, butanediol diglycidyl ether, diglycidylaniline, neopentyl glycol glycidyl ether, cyclohexanedimethanol diglycidyl ether, an alkylene diglycidyl ether, polyglycol diglycidyl ether, polypropylene glycol diglycidyl ether, trimethylolpropane triglycidyl ether, glycerol triglycidyl ether, 4-vinylcyclohexene monooxide, vinylcyclohexene dioxide, methylated vinylcyclohexene dioxide, and the like.

These diluents may be used either alone or in combination.

The curable composition according to one embodiment of the invention may be prepared by mixing the component (A), the component (B), and an optional additional component in a given ratio, and defoaming the mixture using a known method, for example.

The curable composition according to one embodiment of the invention thus prepared produces a cured product that maintains excellent transparency and high adhesion for a long time even when exposed to high-energy light or subjected to a high temperature, and exhibits excellent durability with respect to a change in temperature.

Therefore, the curable composition according to one embodiment of the invention is suitably used as a raw material for producing an optical part or a formed article, an adhesive, a coating material, and the like. Since the curable composition according to one embodiment of the invention can reduce or suppress deterioration in an optical device-securing material due to an increase in the brightness of the optical device, the curable composition may suitably be used as an optical device-securing composition.

2) Cured Product

A cured product according to one embodiment of the invention is obtained by curing the curable composition according to one embodiment of the invention.

The curable composition according to one embodiment of the invention may be cured by heating the curable composition. The heating temperature when curing the curable composition is normally set to 100 to 200° C., and the heating time when curing the curable composition is normally set to 10 minutes to 20 hours, and preferably 30 minutes to 10 hours.

The cured product according to one embodiment of the invention exhibits excellent transparency, heat resistance, and adhesion, and also exhibits excellent durability with respect to a change in temperature.

Whether or not the cured product according to one embodiment of the invention exhibits excellent transparency may be determined by measuring the light transmittance of the cured product. The light transmittance of the cured product is preferably 80% or more at a wavelength of 400 nm and 450 nm, for example.

The cured product according to one embodiment of the invention exhibits high adhesion and excellent heat resistance when the adhesion of the cured product is measured as described below, for example. Specifically, the curable composition is applied to a mirror-finished surface of a silicon chip. The surface of the silicon chip to which the curable composition is applied is placed on an adherend, and compression-bonded to the adherend, and the curable composition is cured by heating. After allowing the resulting product to stand for 30 seconds on the measurement stage of a bond tester that has been heated to a given temperature (e.g., 23° C. or 100° C.), the adhesion between the specimen and the adherend is measured while applying stress to the bonding surface in the horizontal direction (shear direction) at a height of 50 μm above the adherend.

It is preferable that the cured product have an adhesion at 23° C. or 100° C. of 35 N/2 mm square or more, and more preferably 80 N/2 mm square or more.

Whether or not the cured product according to one embodiment of the invention exhibits excellent durability with respect to a change in temperature may be determined by preparing a specimen-bonded adherend in the same manner as in the case of measuring the adhesion, subjecting the specimen-bonded adherend to a heat cycle test, and measuring the adhesion in the same manner as described above.

Specifically, the specimen-bonded adherend is subjected to the heat cycle test in 100 cycles (one cycle consists of an operation that holds the specimen-bonded adherend at −40° C. for 30 minutes, and then holds the specimen-bonded adherend at 100° C. for 30 minutes), and the adhesion between the specimen and the adherend is measured at 23° C. It is preferable that the adhesion thus measured be 30% or more, and more preferably 60% or more, with respect to the adhesion of the specimen at 23° C. that has not been subjected to the heat cycle test.

The cured product according to one embodiment of the invention is suitably used as a raw material for producing an optical part or a formed article, an adhesive, a coating material, a sealing material, and the like. Since the cured product according to one embodiment of the invention can reduce or suppress deterioration in an optical device-securing material due to an increase in the brightness of an optical device, the cured product can suitably be used as an optical device-securing material.

3) Method for Using Curable Composition

A method for using a curable composition according to one embodiment of the invention includes using the curable composition according to one embodiment of the invention as an optical device-securing composition such as an optical device adhesive or an optical device sealing material.

Examples of the optical device include a light-emitting device (e.g., LED and LD), a light-receiving device, a hybrid optical device, an optical integrated circuit, and the like.

Optical Device Adhesive

The curable composition according to one embodiment of the invention may suitably be used as an optical device adhesive.

When using the curable composition according to one embodiment of the invention as an optical device adhesive, the curable composition may be applied to the bonding surface of either or both of the bonding target materials (e.g., an optical device and a substrate), for example. The bonding target materials may be compression-bonded, and the curable composition may be cured by heating to firmly bond the bonding target materials.

Examples of a material for forming the substrate to which the optical device is bonded, include glass (e.g., soda lime glass and heat-resistant hard glass); a ceramic; a metal (e.g., iron, copper, aluminum, gold, silver, platinum, chromium, titanium, alloys thereof, and stainless steel (e.g., SUS302, SUS304, SUS304L, and SUS309)); a synthetic resin (e.g., polyethylene terephthalate, polybuthylene terephthalate, polyethylene naphthalate, ethylene-vinyl acetate copolymer, polystyrene, polycarbonate, polymethylpentene, polysulfone, polyether ether ketone, polyether sulfone, polyphenylene sulfide, polyetherimide, polyimide, polyamide, acrylic resin, norbornene resin, cycloolefin resin, and glass epoxy resin); and the like.

The heating temperature when curing the curable composition is determined taking account of the type of curable composition and the like, but is normally 100 to 200° C. The heating time is normally 10 minutes to 20 hours, and preferably 30 minutes to 10 hours.

Optical Device Sealing Material

The curable composition according to one embodiment of the invention may suitably be used as an optical device sealing material.

When using the curable composition according to one embodiment of the invention as an optical device sealing material, the curable composition may be formed to have the desired shape to obtain a formed article that includes an optical device, and the formed article may be cured by heating to produce a sealed optical device, for example.

The curable composition according to one embodiment of the invention may be formed using an arbitrary method to have the desired shape. A known molding method such as a transfer molding method or a casting method may be used.

The heating temperature when curing the formed article (curable composition) is determined taking account of the type of curable composition and the like, but is normally 100 to 200° C. The heating time is normally 10 minutes to 20 hours, and preferably 30 minutes to 10 hours.

A sealed optical device produced by utilizing the curable composition according to one embodiment of the invention exhibits excellent transparency and excellent heat resistance (i.e., does not show discoloration due to heat or light), even when the optical device has an emission peak wavelength as short as 400 to 490 nm (e.g., white LED or blue LED).

EXAMPLES

The invention is further described below by way of examples and comparative examples. Note that the invention is not limited to the following examples.

Measurement of Weight Average Molecular Weight

The weight average molecular weight (Mw) (polystyrene-equivalent weight average molecular weight) of the silane compound polymer obtained in each production example was determined using the following device under the following conditions.

-   Device: HLC-8220 GPC manufactured by Tosoh Corporation -   Column: TSKgel GMHXL, TSKgel GMHXL, and TSKgel 2000 HXL (that were     sequentially connected) -   Solvent: tetrahydrofuran -   Injection amount: 80 μl -   Temperature: 40° C. -   Flow rate: 1 ml/min -   Detector: differential refractometer

Measurement of IR Spectrum

The IR spectrum of the silane compound polymer obtained in each production example was measured using a Fourier transform infrared spectrometer (“Spectrum 100” manufactured by PerkinElmer).

Production Example 1

A 300 ml recovery flask was charged with 71.37 g (400 mmol) of methyltriethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.), followed by the addition of a phosphoric acid aqueous solution (prepared by dissolving 0.20 g (2 mmol) of phosphoric acid in 21.6 ml of distilled water) at 30° C. with stirring. After the addition of the phosphoric acid aqueous solution, the mixture was stirred at 30° C. for 2 hours, and stirred at 70° C. for 5 hours.

The organic layer was repeatedly washed with purified water until the pH of the aqueous layer reached 4, and concentrated using an evaporator. The concentrate was dried under vacuum to obtain 53.5 g of a silane compound polymer 1. The silane compound polymer 1 had a weight average molecular weight of 8,780 and a molecular weight distribution of 5.25.

The IR spectral data of the silane compound polymer 1 was as follows. Si—CH₃: 1272 cm⁻¹, 1409 cm⁻¹, Si—O: 1132 cm⁻¹

Production Example 2

A 100 ml recovery flask was charged with 9.62 g (50 mmol) of ethyltriethoxysilane (manufactured by Tokyo Chemical Industry Co., Ltd.), followed by the addition of a phosphoric acid aqueous solution (prepared by dissolving 0.025 g (0.25 mmol) of phosphoric acid in 2.7 ml of distilled water) at 30° C. with stirring. After the addition of the phosphoric acid aqueous solution, the mixture was stirred at 30° C. for 2 hours, and stirred at 70° C. for 5 hours.

The organic layer was repeatedly washed with purified water until the pH of the aqueous layer reached 4, and concentrated using an evaporator. The concentrate was dried under vacuum to obtain 5.9 g of a silane compound polymer 2. The silane compound polymer 2 had a weight average molecular weight of 2,150 and a molecular weight distribution of 1.96.

The IR spectral data of the silane compound polymer 2 was as follows. Si—CH₂—: 1253 cm⁻¹, 1415 cm⁻¹, —CH₃: 2882 cm⁻¹, 2964 cm⁻¹, Si—O: 1132 cm⁻¹

Production Example 3

A 100 ml recovery flask was charged with 10.32 g (50 mmol) of propyltriethoxysilane (manufactured by Tokyo Chemical Industry Co., Ltd.), followed by the addition of a phosphoric acid aqueous solution (prepared by dissolving 0.025 g (0.25 mmol) of phosphoric acid in 2.7 ml of distilled water) at 30° C. with stirring. After the addition of the phosphoric acid aqueous solution, the mixture was stirred at 30° C. for 2 hours, and stirred at 70° C. for 5 hours.

The organic layer was repeatedly washed with purified water until the pH of the aqueous layer reached 4, and concentrated using an evaporator. The concentrate was dried under vacuum to obtain 6.2 g of a silane compound polymer 3. The silane compound polymer 3 had a weight average molecular weight of 2,560 and a molecular weight distribution of 1.85.

The IR spectral data of the silane compound polymer 3 was as follows. Si—CH₂—: 1253 cm⁻¹, 1415 cm⁻¹, —CH₃: 2958 cm⁻¹, 2872 cm⁻¹, —CH₂—: 2931 cm⁻¹, Si—O: 1132 cm⁻¹

Example 1

0.5 parts (parts by mass, hereinafter the same) of 3-(trimethoxysilyl)propylsulfanyltriethoxysilane (component (B)) was added to 100 parts of the silane compound polymer I obtained in Production Example 1. The mixture was sufficiently mixed and defoamed to obtain a curable composition 1.

Examples 2 to 32 and Comparative Examples 1 to 5

Curable compositions 2 to 32 of Examples 2 to 32 and curable compositions 1r to 5r of Comparative Examples 1 to 5 were obtained in the same manner as in Example 1, except that each component was used in the ratio shown in Table 1.

The meanings of the symbols A1 to A3, B1, B2, C1, C2, and D1 in Table 1 are as follows.

-   A1: silane compound polymer 1 -   A2: silane compound polymer 2 -   A3: silane compound polymer 3 -   B 1: 3-(trimethoxysilyl)propylsulfanyltriethoxysilane -   B2: 3-mercaptopropyltrimethoxysilane -   C1: 1,3,5-N-tris[3-(trimethoxysilyl)propyl]isocyanurate -   C2: N,N′-bis[3-(trimethoxysilylpropyl)]urea -   D1: 3-(trimethoxysilyl)propylsuccinic anhydride

TABLE 1 Component Component (B) (C1) (C2) (D1) (A) Amount Amount Amount Amount 100 parts Type (parts) (parts) (parts) (parts) Example 1 A1 B1 0.5 — — — Example 2 A1 B1 1.0 — — — Example 3 A1 B1 3.0 — — — Example 4 A1 B1 5.0 — — — Example 5 A1 B1 10.0 — — — Example 6 A1 B1 15.0 — — — Example 7 A1 B1 30.0 — — — Example 8 A1 B2 0.5 — — — Example 9 A1 B2 1.0 — — — Example 10 A1 B2 3.0 — — — Example 11 A1 B2 5.0 — — — Example 12 A1 B2 10.0 — — — Example 13 A1 B2 15.0 — — — Example 14 A1 B2 30.0 — — — Example 15 A1 B1 1.0 10.0 — — Example 16 A1 B1 3.0 10.0 — — Example 17 A1 B1 1.0 10.0 — 1.0 Example 18 A1 B1 3.0 10.0 — 1.0 Example 19 A1 B1 3.0 — — 1.0 Example 20 A1 B2 1.0 10.0 — — Example 21 A1 B2 3.0 10.0 — — Example 22 A1 B2 1.0 10.0 — 1.0 Example 23 A1 B2 3.0 10.0 — 1.0 Example 24 A1 B2 3.0 — — 1.0 Example 25 A2 B2 1.0 — — — Example 26 A2 B2 3.0 — — — Example 27 A2 B2 1.0 10.0 — — Example 28 A2 B2 1.0 10.0 — 1.0 Example 29 A3 B2 1.0 — — — Example 30 A3 B2 3.0 — — — Example 31 A3 B2 1.0 10.0 — — Example 32 A3 B2 1.0 10.0 — 1.0 Comparative A1 — — — — — Example 1 Comparative A2 — — — — — Example 2 Comparative A3 — — — — — Example 3 Comparative A1 — — — 1.0 — Example 4 Comparative A1 — — — 5.0 — Example 5

The adhesion, the adhesion after the heat cycle test, and the transmittance were measured as described below using the cured products of the curable compositions 1 to 32 obtained in Examples 1 to 32 and the curable compositions 1r to 5r obtained in Comparative Examples 1 to 5 to evaluate the adhesion, the heat resistance (high-temperature adhesion), the durability with respect to a change in temperature, and the transparency. The measurement results and the evaluation results are shown in Table 2.

Adhesion Test

The curable composition (curable compositions 1 to 32 obtained in Examples 1 to 32 and curable compositions 1r to 5r obtained in Comparative Examples 1 to 5) was applied to the mirror-finished surface of a silicon chip (2×2 mm) to a thickness of about 2 μm. The surface of the silicon chip to which the curable composition was applied was placed on an adherend (silver-plated copper sheet), and compression-bonded to the adherend. The curable composition was cured by heating at 170° C. for 2 hours to prepare a specimen-bonded adherend. After allowing the specimen-bonded adherend to stand for 30 seconds on the measurement stage of a bond tester (“Series 4000” manufactured by Dage Co., Ltd.) that had been heated to a given temperature (23° C. or 100° C.), the adhesion (N/2 mm square) (23° C. and 100° C.) between the specimen and the adherend was measured while applying stress (speed: 200 μm/s) to the bonding surface in the horizontal direction (shear direction) at a height of 50 μm above the adherend.

Evaluation of Durability with Respect to a Change in Temperature

A specimen-bonded adherend was prepared in the same manner as described above (see “Adhesion test”). The specimen-bonded adherend was subjected to the heat cycle test in 100 cycles (one cycle consists of an operation that holds the specimen-bonded adherend at −40° C. for 30 minutes, and then holds the specimen-bonded adherend at 100° C. for 30 minutes) using a thermal shock tester (“TSA-71 S” manufactured by ESPEC Corporation). After the heat cycle test, the adhesion between the specimen and the adherend was measured in the same manner as described above.

A case where the adhesion between the specimen and the adherend measured after the heat cycle test was 60% or more with respect to the adhesion measured at 23° C. during the adhesion test was evaluated as “A”, a case where the adhesion between the specimen and the adherend measured after the heat cycle test was 30% or more and less than 60% with respect to the adhesion measured at 23° C. during the adhesion test was evaluated as “B”, and a case where the adhesion between the specimen and the adherend measured after the heat cycle test was less than 30% with respect to the adhesion measured at 23° C. during the adhesion test was evaluated as “C”.

Measurement of Transmittance

The curable composition (curable compositions 1 to 32 obtained in Examples 1 to 32 and curable compositions 1r to 5r obtained in Comparative Examples 1 to 5) was poured into a mold so as to have a length of 25 mm, a width of 20 mm, and a thickness of 1 mm, and cured by heating at 140° C. for 6 hours to prepare a specimen. The transmittance (%) (wavelength: 400 nm and 450 nm) of the specimen was measured using a spectrometer (“MPC-3100” manufactured by Shimadzu Corporation).

TABLE 2 Durability with respect Adhesion to change Curable (N/2 mm in Transmittance com- square) tem- (%) position 23° C. 100° C. perature 400 nm 450 nm Example 1 1 100.6 53.3 A 90.3 93.2 Example 2 2 144.0 54.2 A 90.2 93.6 Example 3 3 258.4 71.2 B 90.1 92.1 Example 4 4 213.1 112.7 A 89.2 92.8 Example 5 5 191.6 100.9 A 89.5 92.9 Example 6 6 152.9 82.6 A 87.9 90.9 Example 7 7 117.8 66.3 A 86.0 88.8 Example 8 8 155.7 88.8 A 90.3 91.3 Example 9 9 196.6 128.9 A 90.6 92.6 Example 10 10 217.1 98.5 A 89.2 92.1 Example 11 11 220.2 154.8 A 89.9 91.8 Example 12 12 213.1 98.8 A 89.7 91.5 Example 13 13 145.6 88.1 A 87.3 90.3 Example 14 14 150.8 65.4 A 86.7 89.0 Example 15 15 157.3 67.8 A 89.3 91.0 Example 16 16 118.0 78.2 A 88.9 91.6 Example 17 17 208.2 150.2 A 88.3 92.2 Example 18 18 159.2 157.8 A 88.3 91.3 Example 19 19 164.1 99.9 A 87.9 91.6 Example 20 20 177.9 125.5 A 87.3 90.7 Example 21 21 152.9 136.2 A 88.5 91.5 Example 22 22 215.4 155.6 A 88.4 91.2 Example 23 23 168.5 130.5 A 88.2 92.3 Example 24 24 154.2 101.4 A 88.7 93.0 Example 25 25 126.9 92.5 A 88.2 92.5 Example 26 26 145.6 100.7 A 87.9 92.8 Example 27 27 149.1 103.4 A 87.1 93.0 Example 28 28 197.2 139.6 A 88.3 91.8 Example 29 29 135.0 107.9 A 88.5 92.6 Example 30 30 152.5 126.7 A 88.2 92.7 Example 31 31 152.1 131.5 A 87.1 92.6 Example 32 32 187.6 142.5 A 87.9 92.0 Comparative 1r 40.0 33.7 C 89.3 93.9 Example 1 Comparative 2r 40.2 27.1 C 88.3 93.1 Example 2 Comparative 3r 42.7 22.1 C 88.7 93.4 Example 3 Comparative 4r 0.37 1.24 C 88.3 92.4 Example 4 Comparative 5r 0.51 1.63 C 88.7 91.5 Example 5

The following were confirmed from the results shown in Table 2.

The cured products of the curable compositions obtained in Examples 1 to 32 exhibited excellent adhesion, excellent durability with respect to a change in temperature, and excellent transparency. In particular, better adhesion was obtained when the components (B), (C), and (D) were used in combination.

On the other hand, the cured products of the curable compositions of Comparative Examples 1 to 5 in which the component (B) was not used exhibited low adhesion and poor durability with respect to a change in temperature. 

1. A curable composition comprising a component (A) and a component (B) in a mass ratio (component (A):component (B)) of 100:0.1 to 100:50, the component (A) being a silane compound polymer that is represented by a formula (a-1), (R¹SiO_(3/2))_(m)(R¹SiZO_(2/2))_(n)(R¹SiZ₂O_(1/2))_(o)   (a-1) wherein R¹ is a group selected from an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, and a substituted or unsubstituted aryl group having 6 to 20 carbon atoms, Z is a hydroxyl group, an alkoxy group having 1 to 10 carbon atoms, or a halogen atom, m is a positive integer, and n and o are independently 0 or a positive integer, provided that a plurality of R¹ are either identical or different, and a plurality of Z are either identical or different, and the component (B) being a silane coupling agent that comprises a sulfur atom-containing functional group in its molecule.
 2. The curable composition according to claim 1, wherein the silane compound polymer used as the component (A) has a weight average molecular weight of 1,000 to 30,000.
 3. The curable composition according to claim 1, wherein the silane coupling agent used as the component (B) is a compound among compounds respectively represented by fo1mulas (b-1) to (b-4), (Y¹)₃Si-A¹-SH   (b-1) (Y¹)₃Si-A¹-S—CO—R′  (b-2) (Y¹)₃Si-A¹-S—Si(Y²)₃   (b-3) (Y¹)₃Si-A¹-(S)_(n)-A²-Si(Y²)₃   (b-4) wherein Y¹ and Y² are independently an alkoxy group having 1 to 10 carbon atoms, A¹ and A² are independently a substituted or unsubstituted divalent hydrocarbon group having 1 to 20 carbon atoms, R′ is a monovalent organic group having 1 to 20 carbon atoms, and n is an integer from 1 to 4, provided that a plurality of Y¹ are either identical or different, and a plurality of Y² are either identical or different.
 4. The curable composition according to claim 1, further comprising a component (C), the component (C) being a silane coupling agent that comprises a nitrogen atom-containing functional group in its molecule.
 5. The curable composition according to claim 4, wherein the silane coupling agent used as the component (C) is a compound among compounds respectively represented by formulas (c-3) to (c-6),

wherein R^(a) are a hydroxyl group, an alkoxy group having 1 to 10 carbon atoms, or a halogen atom, R^(b) are an alkyl group having 1 to 6 carbon atoms, or a substituted or unsubstituted aryl group, provided that a plurality of R^(a) are either identical or different, and a plurality of R^(b) are either identical or different, and t is an integer from 1 to
 10. 6. The curable composition according to claim 1, further comprising a component (D), the component (D) being a silane coupling agent that comprises an acid anhydride structure in its molecule.
 7. The curable composition according to claim 6, wherein the silane coupling agent used as the component (D) is a 3-(tri(C₁₋₆)alkoxysilyl)propylsuccinic anhydride.
 8. The curable composition according to claim 1, the curable composition being an optical device-securing composition.
 9. A cured product obtained by curing the curable composition according to claim
 1. 10. The cured product according to claim 9, the cured product being an optical device-securing material.
 11. A method for using the curable composition according to claim 1 as an optical device-securing adhesive.
 12. A method for using the curable composition according to claim 1 as an optical device sealing material. 